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Ihearmusic

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About Ihearmusic

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  • Birthday 05/12/1963

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    Perth
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    Australia

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  1. I know where you are coming from Con, nothing wrong with that. The manufacturer's recommendations are one the very safe side for obvious reasons. But since he has an open back, airflow should not be a problem. I would love to know how much airflow he gets through those glass tubes though.......
  2. I do not think you would have any problems with that.
  3. The heat source are the power tubes. Looking at your amp one would hope that there is some opening at the bottom of the amps so an updraft of cool air can keep them power valves in those glass cylinders from getting to hot. I might consider getting rid of the glass cylinders then it would be happy to sit inside a shelf with reasonable ventilation. Heat build up inside the chassis would be bad for capacitors.
  4. Like the caption says, "nearly half way there". The Mono's are finished now and the stickers are inside the chassis.
  5. I put pen to paper and I hope it is legible.
  6. The impedance of the primary of the output transformer is a reflection of the impedance of the speaker hooked up to the secondary. The operating point of the power tubes is based around the primary impedance. If you were to hook up speakers on two different taps the primary impedance would will be way off. Were you to hook up a 4 ohm speaker to a 8 ohm tap for example, depending on the turns ratio of the OPT, you could find yourself in a situation where you have twice the current running through the tube. This could to some serious damage to the amplifier. Going the other way is not so much of a problem, but again, the tube will not work at the operating point it was set out to work in for optimal performance.
  7. A bit of a leap from home audio to studio gear but whatever floats your boat.
  8. I rather have any of the above then one of these cheap looking things.
  9. The question about speaker compatibility (deanB is asking) is valid. Tube unfriendly speakers might have a too big a drop in impedance (not so much a problem for a tweeter). With only 24 Watt output into badly matched speakers you will just miss out on to music. A lack of bass and midds cannot likely by fixed with a change of capacitors.
  10. And of course there is the time lag between changing caps. Unless there is a significant difference in sound quality, it is very hard to A-B test.
  11. The question that needs to be asked; Is there a problem, or are you just after a different sound? What is it you are missing? Mid range? Bass? To harsh? To Mushy? Have you heard better somewhere else? Capacitor change in a tube amp of some reputation may just mean a side step or a down grade.
  12. That old chestnut again. To my mind, global negative feedback is used to fix problems like unstable drive/split stage and/or to correct excessive distortion from careless designs. The little difference it make in a valve amp in regards to the damping factor are inconsequential. But this in only my opinion. I have yet to build a tube amp with GNF. So far I have had no call for it. In a given situation, this may very well be true. Rs is a byproduct of negative feedback. The more such feedback that is thrown into a power amplifier circuit, the lower the generator impedance and the higher the damping factor. The point is simply that if a lot of feedback has to be used to lick the distortion in a particular circuit, fine - use it. But don't believe that the reason it sounds good because of some astronomically high damping factor. When I get a letter from someone who is worried about buying a certain amplifier because it has a specified damping factor of "only" 15 to 16, I can't help but remember an old, old joke. It goes like this: A scientist is giving a public lecture. During the course of his speech, he predicts that in 100 billion years human life will become extinct. A man in the audience, obviously upset, asks the lecturer to repeat the statement. "I said", quotes the professor, "that in one hundred billion years, human life will no longer exist." "Oh, thank goodness", replies the man, much relieved, "I thought you said one-hundred million!".
  13. At 40w output you don't need very high efficient speakers. As long as the speakers don't dip to much bellow the nominated impedance it will be fine. Feedback or not does not mean you will have to have a certain type of speakers either. The amp will likely come with an 8 ohm tap with options for others. Good on Mick for adding a power amp to his range and good luck to him.
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